I need to call a routine inside a loop which takes a text file as input. Because I don't want to open and close the text file all the time I keep it open in the loop. For Example:
with open("test.txt",'r+') as w_file:
w_file.write(str(0.8) + "\n" + str(0.2))
subprocess.call(["cat","test.txt"]) #Here I want to call my routine
But the file is still in the old state. Why? And whats the best way to handle this?
you need to close the file after writing. try:
with open("test.txt",'r+') as w_file:
w_file.write(str(0.8) + "\n" + str(0.2))
subprocess.call(["cat","test.txt"]) #Here I want to call my routine
or without closing, flush the file
with open("test.txt",'r+') as w_file:
w_file.write(str(0.8) + "\n" + str(0.2))
w_file.flush()
subprocess.call(["cat","test.txt"]) #Here I want to call my routine
w mode instead of r+ to overwrite the file.This should work:
with open("test.txt",'r+') as w_file:
w_file.write(str(0.8) + "\n" + str(0.2))
w_file.flush()
subprocess.call(["cat","test.txt"])
The method "flush" syncs the actual file referenced by the file-like object w_file with the contents still in memory, so when you reference the file by it's name (and not the w_file FLO), you see an up to date version.
w_file.flush()after yourwriteline, but before thesubprocess.callline.print()function:print(0.8, 0.2, sep="\n",file=w_file)or string formatting:w_file.write("{}\n{}".format(0.8, 0.2))